1. Field of the Disclosure
The present disclosure relates to devices and methods for perforating a formation.
2. Description of the Related Art
Hydrocarbons, such as oil and gas, are produced from cased wellbores intersecting one or more hydrocarbon reservoirs in a formation. These hydrocarbons flow into the wellbore through perforations in the cased wellbore. Perforations are usually made using a perforating gun loaded with shaped charges. The gun is lowered into the wellbore on electric wireline, slickline, tubing, coiled tubing, or other conveyance device until it is adjacent the hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow through the perforations and into a production string.
Shaped charges used in perforating oil wells and the like typically include a housing which is cylindrical in shape and which is formed from metal, plastic, rubber, etc. The housing has an open end and receives an explosive material having a concave surface facing the open end of the housing. The concave surface of the explosive material is covered by a liner which functions to close the open end of the housing. When the explosive material is detonated, a compressive shock wave is generated which collapses the liner. The inner portion of the liner is extruded into a narrow diameter high-speed jet which perforates the casing and the surrounding cement comprising the oil well, etc. The remainder at the liner can form a larger diameter slug which can follow the high-speed jet into the perforation, thereby partially or completely blocking the perforation and impeding the flow of oil therethrough.
While shaped charges have been in use for oilfield applications for decades and the behavior and dynamics of the jets formed by shaped charges have been extensively studied, traditional shaped charge designs do not yet take full advantage of the amount of explosive used and/or the amount of liner available to form a jet. The present disclosure addresses these and other drawbacks of the prior art.